Justin Sullivan plotted to kill hundreds of people in North Carolina and Virginia on behalf of the Islamic State and wanted a silencer for a gun. So he had one built from a flashlight and delivered to the Morganton, N.C., house he shared with his parents. When his parents asked what he planned to do with it, he tried to have them killed.

The person he offered to pay to kill his parents and who sent him the silencer was an undercover FBI employee. Sullivan, 20, admitted his plot on Tuesday…